As the quality and number of features of audio and video (“A/V”) devices have increased, the complexity of integrating and controlling these devices has also increased. It has been a common trend to place the burden of dealing with this ever-increasing complexity primarily upon the end users. This burden will increase as digital A/V devices are slowly integrated with analog A/V devices.
Digital A/V devices, such as those devices that comply with the standards promulgated in IEEE 1394-1995 Standard for a High Performance Serial Bus, P1394/Draft 7.1v1, published Aug. 5, 1994 (and other 1394-based standards such as the Home Audio/Video Interoperabilitiy (“HAVi”) Architecture, ver. 0.8, published May 11, 1998), promise benefits such as higher data throughputs, higher quality audio, increased resolution video, decreased data degradation, etc. while also promising ease-of-use. However, the promise of easier-to-use A/V devices can only be fully realized if end users replace all of their existing analog devices with digital devices. For most people, this type of wholesale replacement of existing devices would involve an unrealistic capital investment. In addition, there is no guarantee that all digital devices will fully comply with a single standard such as the IEEE 1394 standard. Therefore, there will undoubtedly be a transition phase for most end users during which their A/V devices may consist of a mixture of analog devices and digital devices that may or may not comply with a single digital standard. And as a result of this disparate mixture of analog and digital devices, configuring and controlling these devices may actually be more difficult.
A first conventional approach to addressing the increasing complexities of A/V devices is through the use of a universal remote control system with macro capabilities. In this system, a remote control device has the capability to receive a set of button-initiated commands (e.g., in order to record a program on channel 7, the user may press a first button to initiate sending commands to a television, press the “7”+Enter button to change the channel to 7, press another button to initiate sending commands to a video cassette recorder (“VCR”), and then press the record button to have the VCR record the program on channel 7) and store these button-initiated commands in a memory device as a macro. Then, at any time, the user only needs to invoke the macro to repeat the set of commands stored therein. Although this macro-type of control system enables an end user to store a complex set of commands and easily repeat them, there are several shortcomings. First, the user must know the proper sequence of commands needed to perform a specific task. Second, the remote control device must be capable of controlling all of the various devices necessary to perform a specific task. Third, any change in the devices or configuration of the devices would require a modification or re-recording of the macros or the remote control device.
In another conventional system, the A/V devices are controlled by a computer using various communications methods to convey command signals to the devices. For example, the devices may be controlled by the computer via a serial cable (e.g., as in the IEEE 1394 standard), an infrared (“I/R”) transmitter or a radio frequency (“RF”) transmitter. Due to the various communications methods that may be used by the computer to control the A/V devices, this type of system may be used to control both digital and analog A/V devices. Each A/V device is represented as a software object on the computer. These software objects include device-specific command sets which may be accessed by the computer's processor to operate the corresponding A/V devices. Programmers may then write control programs providing a user-friendly interface that allows the user to indirectly access the command sets to control the various A/V devices without any understanding of the software objects or the command sets. However, these conventional systems merely provide an improved interface system for controlling the individual A/V devices, without simplifying the integration process.
In yet another conventional system, the personal computer is implemented as a data router/data termination device for A/V devices. In these systems, data signals from A/V devices are received by the computer, and are either routed to another A/V device or rendered by the computer. For example, a stereo system may send audio signals to the computer, and the computer may send the audio signals to a speaker system that is also connected to the computer. In another example, a VCR may send both audio and video signals to the computer. The computer may then render the video signals on a monitor and route the audio signals to a speaker system. In this manner, the computer controls the A/V devices and is also directly involved in routing the data signals to the appropriate devices.
MICROSOFT®'s DIRECTSHOW™ is an example of a system that implements this type of computer-based system for integrating and controlling A/V-type devices, in which multimedia data is streamed between the devices through the computer. DIRECTSHOW™ processes multimedia data through software objects called filters. Filters are software objects that perform certain tasks required to process the multimedia data, such as reading the multimedia file from a disk, transforming the data, or rendering the multimedia data. Each filter has either an input pin, output pin or both depending on the function the specific filter is performing. The computer runs a filter graph manager that constructs filter graphs, which is a connection of the various filters via their respective pins, to render specific multimedia data. The construction of the filter graph is performed as a function of the type of data that needs to be rendered and the transformations that must be performed before the data can be rendered.
However, applying the current DIRECTSHOW™ system in the home A/V device context would have certain drawbacks. In the DIRECTSHOW™ system, the data is routed through the computer which may be acceptable for controlling computer-related devices, but impractical for controlling devices where there is absolutely no need for the data to pass through the computer. For example, watching a program from a satellite dish on a television does not require that the data be routed through the computer. In addition, DIRECTSHOW™ is limited in its ability to handle certain problems such as widespread distribution of equipment, resource reservation, etc. which will be further discussed below in relation to the present invention.